1. Field of the Invention
The present invention relates generally to a load-force-resisting assembly, and specifically to a pallet or dunnage support constructed of paperboard that minimizes adverse environmental impact, occupies little space before it is configured, and effectively saves production, storage, and transportation costs.
2. Description of Related Art
A pallet is primarily used to handle materials in large quantities and typically comprises a flat, elevated surface to support containers or packages a sufficient distance from a surface such as a floor to permit the forks of a forklift to be inserted under them so that the pallet supporting the load can be moved from place to place. For the purpose of transporting products, using pallets to carry goods is simple, economical, and efficient.
Most pallets have been made of wood. Of the available materials prior to a new technology in paperboard construction being developed, softwood provided the best balance of both strength and cost.
However, a number of problems face users of conventional wooden pallets. The cost of making and repairing wooden pallets is rising at a rate that is detracting from the cost effectiveness of palletized shipment. Moreover, empty wooden pallets require substantial space for storage, and it is especially costly to transport empty pallets by rail or truck for reuse.
In an effort to reduce costs, many wood pallet producers have resorted to using lower grades of unseasoned or untreated lumber commonly known as “pallet lumber.” Pallet lumber typically has a rough finish and is prone to cracking, warping, or the like. Further, such rough finishes present a splinter hazard and are unsuitable for some uses, including food-handling applications. Such low grades of lumber also readily split or break, resulting in pallet failure.
Conventional types of pallets must be returned to the shipper after use so the shipper can reuse them, if possible, or the pallets have to be disposed of in a proper manner. Yet, wood pallets are bulky which makes them inconvenient to store and return to the shipper. Damaged wooden pallets generally cannot be taken to a landfill or other waste disposal site. Rather, they must be reduced either by chipping or burning before disposal. Chipping is a significant problem inasmuch as nails and other metal fasteners must be removed from the pallet wood before the chipping operation can be undertaken, adding significant cost to pallet reduction. By the same token, increasingly stringent environmental regulations often preclude the burning of used pallets.
Disposal of the conventional wood and nail pallets is a more serious problem when such pallets are exposed to chemical or biochemical materials that contaminate the pallet, since contaminated parts of the pallet can not be destroyed through incineration. The contaminated parts of the pallets often must be disposed in a hazardous waste landfill, which disposal is also inconvenient and expensive.
As forest resources also have been declining in recent years, pallets constructed of plastic and metal have been developed. While it is true that higher pressure-resistant strength is an advantage of pallets made of plastic and metal, in terms of environmental protection these two other types of pallet material no longer meet the requirements of environmental preservation. Additionally, the heavier pallet materials of plastic and metal pallets do not satisfy economic efficiency when weight is the basis for the calculation of transportation costs.
Thus there has been a long-felt need for a pallet that is lightweight, inexpensive, and strong, and has smooth outward surfaces, that is formed of an alternate material other than wood, plastic, or metal.
A demand presently exists for recyclable materials such as corrugated paperboard boxes that may be readily remanufactured into recycled corrugated paperboard. Recyclability provides future cost efficiencies on a large scale. Paperboard is a largely homogenous material (with the exception of minor amounts of adhesive and printing ink, which are acceptable in the recycling process) and may be readily collected at a number of discrete sites (e.g., warehouse, factory, retail store, or the like). In some instances, pallets are used to support a number of corrugated containers (e.g., boxes) which may be attached to the pallet using suitable means (e.g., strapping, shrink-wrapping, or the like). Thus it is desirable to provide a pallet that can be recycled in the same material stream as its accompanying corrugated containers.
There have been a variety of attempts over the years to replace wooden pallets with those constructed of paperboard. However, past paperboard pallets were not as sturdy as wooden pallets, were more costly, and required inside storage, and none of them received widespread acceptance. In recent years, attempts also have been made to replace the bulky and expensive wooden pallets with solid paperboard sheets called slip-sheets. These slip-sheets simply comprise a sheet of solid paperboard that is slightly larger than the dimensions of the goods to be stacked thereon. The slip-sheet is neither intended for nor capable of supporting the weight of the stacked goods, and must always be supported on a suitable horizontal surface, by using a conventional pallet, or handled with specially designed equipment. By providing an extra marginal edge of solid board material, it is possible to grasp and slide the sheets and the goods carried thereon about the floor or onto a specially designed lift truck.
While slip-sheets have provided cost savings in many industrial situations, they simply are not suitable to fully replace palletized shipments. For example, difficulties have been encountered where heavily loaded slip-sheets are positioned directly adjacent the doorway of a fully loaded boxcar or truck trailer. When so positioned, the lift truck mechanism is unable to grasp a sufficient portion of the slip-sheet to pull it onto the lift truck. A slip-sheet improperly grasped is often ripped. This has necessitated, in many situations, unloading the sheet to move the goods out of the carrier and then restacking the goods on the sheet for transport by a lift truck.
An all-corrugated paperboard pallet is desirable, as it can be recycled along with any corrugated containers carried on the pallet. In warehouses and retail stores it is known to provide a separate compactor for compacting and storing corrugated waste. Such waste can then be retrieved and recycled into new corrugated material. In addition to the designs noted above, several attempts have been made to produce an all-corrugated paperboard pallet by mimicking the design of a wood pallet, using layers of corrugated paperboard in place of wood boards. Such pallets are heavy and expensive, as they attempt to achieve the equivalent strength of a wood pallet, and comprise several layers of corrugated material (e.g., as many as 16 layers).
Another requirement of a practical pallet design is that the pallet be suitably moisture and water resistant. Water spills, rain, and condensation may be present in warehouses, loading docks, trucks, railcars, and the like. In many instances a pallet may be placed in proximity to a location where a risk of flooding may occur leaving the pallet placed in a small amount of standing water. Corrugated paperboard pallets of the prior art are not suitably equipped to sustain such moisture conditions. Moreover, alternative pallet designs of paper core, wood, and paper pulp will often disintegrate under such conditions.
A novel corrugated paperboard pallet design is desired that is capable of overcoming the numerous disadvantages of the conventional pallet, and can be made from a converted or remanufactured paper product. In most applications, the corrugated paperboard is a layered structure that is usually die-cut to form corrugated structures. It consists of a fluted corrugated medium sandwiched between sheets of linerboard. The simplest three-ply structure is known as “double wall.” As recently as 1990, much of the linerboard was made entirely from virgin, long-fibered, softwood, kraft pulp. At present, however, these board grades contain sizeable portions of recycled old corrugated containers (OCC) and many are made from 100% OCC.
Around the country, and even in the rest of the world, landfill space for waste disposal is rapidly reaching capacity. By the year 2000, paper and paperboard products are projected to represent 40.9 percent of the municipal solid waste stream and may climb to nearly 42 percent by 2010. New governmental regulations and the public's increasing concern for the environment have created pressure to remove these materials from the solid waste stream. The most widely utilized method of reducing paper waste is recycling.
OCC has a history of efficient recycling use. Even before the era of government mandates and self-imposed industry goals, almost 50% of OCC was recycled in North America. The recovery rate as of 1999 was about 62%. Past estimates indicated that a level of 70% would be achieved by the year 2000. Most of this recycled material goes directly from retail chain stores and factories to mills based on long-term contracts. The rest comes from municipal curbside collection and wastepaper dealers. Some OCC is used in the production of boxboard, and some is even bleached and used in the production of fine paper, but most OCC is used again to produce corrugating medium and linerboard. “Repulping” refers to any mechanical action that disperses dry or compacted pulp fibers into a water slush, slurry or suspension. The action can be just sufficient to enable the slurry to be pumped, or it can be adequate to totally separate and disperse all the fibers. In a typical recycling process, bales of OCC are fed into a repulper, where the material is disintegrated and the gross contaminants are removed. The resulting stock is pumped through pressure screens and cyclonic cleaners to remove oversized materials and foreign matter. Reverse cleaners remove plastics, STYROFOAM® or other lightweight contaminants. The glue, staples, wax, and tapes originally used to assemble the corrugated box must be removed.
Untreated OCC usually creates no problems for recycling. However, paperboard is often treated or coated to enhance its performance and these coatings render the paper unrecyclable. For example, corrugated paperboard is often treated with a curtain coating, wax impregnation, lamination, sizing, or a water-based coating to reduce abrasiveness and to provide for oil and moisture resistance. Moisture vapor transfer rate (MVTR) is a scientific measurement used to describe a product's ability to allow moisture vapor to pass through it, over a specific time period, at a controlled temperature and at a designated atmospheric pressure. While coatings such as wax enhance the moisture-resistance properties of the paperboard, the wax coating process is expensive and often renders the paperboard unrecyclable.
In pallet construction, excessive moisture gain can cause a corrugated paperboard pallet to lose its integrity and fail during use, which potentially could lead to heavy economic losses. Traditional solutions generally involve plastic film, either as a laminate with the paperboard or as a bag around the pallet. Both solutions are expensive or incur added labor costs, and greatly reduce or eliminate the recyclability of the pallet. Therefore, there exists a need in the art for coatings that can provide the high moisture resistance needed without compromising the recyclability of the pallet.
The MVTR of a corrugated paperboard pallet is dependent not only upon the coating on the paperboard, but also the method by which that coating is applied. Traditional methods of coating application, such as a rod coater or a blade coater, may result in variations in coating thickness that will cause variations in the MVTR of the coating. The typical solution to this problem has been to merely increase the amount of coating applied to the paperboard. This solution can be expensive and does not result in a consistently coated product both linearly and across the paperboard web.
Conventional dunnage support assemblies are frequently employed when transporting industrial articles from one location to another. Known dunnage support assemblies typically comprise a dunnage support member that is secured to a rigid frame. The dunnage support member itself is formed of an elastomeric material and has a surface adapted to engage and support the dunnage for transportation. The elasticity of the dunnage support member protects the dunnage from damage that might otherwise result from jarring and vibration during transport.
There have been a number of previously known shipping containers for dunnage, specifically shipping containers for heavy industrial components, such as automotive engines. These previously known shipping containers typically comprise a frame constructed of a rigid material, such as tubular steel. Furthermore, each container is usually designed to transport a number of the industrial components.
Typically, these elastomeric dunnage support members are formed from polyisocyanate that reacts with a resin. The reaction itself is carried out within a mold so that the mold, which conforms in shape to the dunnage support member, forms the part in the desired final shape. Such dunnage support members further can be custom fabricated for the particular dunnage to be transported.
The disposal of previously known dunnage supports after their useful life, however, presents problems, not unlike the problems associated with damaged wood and plastic pallets. The elastomeric material formed by the reaction of polyisocyanate and resin cannot be recycled and, instead, must be disposed of in a landfill or an equivalent. Such disposal is not only expensive, but also presents potential hazards to the environment.
U.S. industry has been moving toward the elimination of foam dunnage supports and packaging comprising polystyrene and other foams, principally because of adverse environmental impacts of such type packaging, and accordingly, efforts are directed toward providing a dunnage support that is recyclable. Industries utilizing dunnage supports are varied, and span from the furniture industry to the automobile industry. Any product that is shipped can be protected from scratches, dents, and other forms of damage by some sort of dunnage support assembly.
The elastomeric material formed for use as a dunnage support generally is an isomeric material that is spongy. Consequently, once the products are wedged between spaced-apart dunnage support members, the spongy elastomeric material compresses slightly and cushions the dunnage. Another disadvantage of the conventional dunnage support assembly is that the shipping container is often subjected to high impact during transport. This is especially true when train transports the shipping container. In such situations, the spongy dunnage support members have been known to crumble or otherwise abrade during transport. Such abrasion or crumbling of the elastomeric material is unacceptable since it can result in damage to the dunnage.
Currently wooden and plastic dunnage supports are also known to be used. These materials form supports, however, that are substantially unyielding, which promotes the packaging of the supported components to rely solely upon the internal protection of the individual container in which the material being shipped is encased.
Thus it can be seen that there is a need for a force-resisting structure that upon construction can be used both as a pallet or a dunnage support, which structure comprises board that is capable of minimizing both environmental pollution and transportation expenses, occupying little space before it is configured, and effectively saving production and storage costs. Preferably, the paperboard pallets and dunnage support assemblies should have a low moisture vapor transmission rate, excellent glueability, and recyclability.